1. Field of the Invention
The invention to method for processing telephone calls and, more particularly, to a method and device for automatically providing an automatic prefix dialer to specifically determined xe2x80x9coutgoingxe2x80x9d or xe2x80x9coutboundxe2x80x9d telephone calls.
2. Description of Related Art
Long-distance Carrier (IXC) Access Codes or Primary interLATA Carrier (PIC) codes identify individual carriers. These codes can be dialed as prefixes by subscribers seeking the least-cost route for their long-distance and international calls. Flexibility and low-cost are the main attractions to the subscriber. In the absence of registration or entry fees, changing carriers is easy. However, the need to dial an identifying prefix can limit the appeal of PIC code dialing.
Alternate access servicers, such as xe2x80x9cdial-aroundxe2x80x9d service providers often offer customers low-cost long distance calling by dialing 10-10-XXX. Dial-around service providers typically rely on direct mail and television advertising to attract customers. Furthermore, to use the service, the customer must remember seven additional digits to dial, in addition to the telephone number he or she is calling. Given the large number of dial-around service providers available to a customer, in order to keep its customers, the dial-around service provider must use direct mail, television advertising and/or other forms of advertising and promotion on a continuous and recurring basis. There are several significant inherent weaknesses in this advertising approach, particularly the high cost of advertising and low customer retention. Thus, to retain-a dedicated client base, the dial-around must continually invest in advertising.
Accordingly, what is needed in the art, is a device which will automatically supply a prefix dialer to certain outgoing calls without any action or assistance from the caller, beyond the caller dialing the intended telephone number. It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed.
The present invention provides an automated prefix dialing system to allow a subscriber/user to automatically insert a predetermined prefix dialing code in certain outgoing telephone call situations. With use of the present invention, the prefix digits are not manually entered prior to dialing. The system is electrically disposed between the telephone company""s central office circuit and the subscriber""s circuit. The system preferably comprises six sub-circuits, namely (1) a DC power path circuit, (2) a ring detector circuit, (3) an isolation circuit, (4) an off-hook sensor circuit, (5) a DTMF receiver and generator circuit, and (6) a micro controller circuit.
When not in use, no power is used by the system. The DC power path circuit, provides power to the various circuits and components of the system when the subscriber""s phone is taken off-hook. The power is received from the central office""s telephone line. Thus, the DC power path portion of the system uses the direct current from the central office network and maintains constant voltages to the circuits within the system.
Off-hook sensor circuitry detects when the telephone has been lifted either in response to an incoming call or to initiate an outgoing call. When the phone is taken off-hook power is taken by the system from the central office line to perform the various functions of the invention. The shadow ring circuit informs the system if the phone is taken off hook because of an incoming call. If so, the system does not get involved with the telephone call as it does not require the insertion of prefix digits. The shadow ring circuit functions without any power supply, by charging a capacitor of the circuit from voltage received from the central office ring signal, prior to the phone being taken off hook. Once the phone is taken off hook, the microprocessor circuit checks for a charge on the capacitor. If a charge is present, the system knows that the phone was taken off hook to answer an incoming call. Where no charge is present on the capacitor, the system knows that the user is initiating an outgoing call, thus requiring analysis by the system to determine whether or not prefix digits should be inserted before the number being dialed by the user.
When analysis is required (outgoing call), the isolation circuit isolates the subscriber""s phone from the central office line to allow the system to analyze the number being dialed by the user without the central office receiving dial tones. If the number satisfies certain calling conditions (long-distance, international, etc.) the programmed prefix digits are automatically inserted before the number by the system. Whether or not prefix digits are inserted, DTMF tones, representing the number dialed by the user, must be generated by the system and are ultimately transmitted to the central office line, with or without the prefix digits.
The DTMF receiver circuit of the system provides amplification to and detection of DTMF signals received from either the subscriber telephone or central office. The processor of the system monitors either tones from the subscriber""s telephone or from incoming DTMF tones from central office. It is these DTMF signals that are analyzed to determine whether or not any prefix digits should be inserted before the number dialed by the user.
The DTMF generator circuit generates the DTMF signals corresponding to any prefix digits to be inserted and the number originally entered by the user and forwards such signals to the central office line. At this point, the isolation is removed and the subscriber is reconnected to the central office line. It should be recognized that the present invention is not limited to any specific number of prefix digit(s), and all are considered within the scope of the invention. The present invention can also be designed and/or programmed for use with an extension phone, where a digit/number (i.e. xe2x80x9c9xe2x80x9d) is first entered to get an outside line.
Accordingly, it is an object of the present invention to automatically insert a programmed prefix digit code for certain specifically determined outgoing long-distance and international telephone calls.
It is another object of the present invention to provide an automatic prefix dialer which operates from power received from the central office""s phone lines.
It is still another object of the present invention to detect when a subscriber""s phone has been taken off-hook to answer an incoming call without any power being supplied to the detection circuitry.
It is yet another object of the present invention to provide an automatic prefix dialer that isolates the subscriber""s phone from the central office line while the dialer is analyzing the number being dialed/entered by the subscriber/user.
It is even still another object of the present invention to provide an automatic prefix dialer which help reduce advertising costs of a xe2x80x9cdial aroundxe2x80x9d service provider.
It is yet still another object of the present invention to provide an automatic prefix dialer which will help a xe2x80x9cdial aroundxe2x80x9d service provider to maintain its customer base.
It is a further object of the present invention to provide an automatic prefix dialer which is relatively low in cost.
It is an even further object of the present invention to provide an automatic prefix dialer which is relatively easy to connect between the central office phone line and subscriber""s phone and relatively easy to install/program by the subscriber.
In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings.